The invention relates to a camshaft adjuster for an internal combustion engine the adjuster being mounted to the camshaft by a hollow screw which includes a control piston operable by an electromagnetic operating mechanism.
To lower fuel consumption and untreated emissions as well as increasing the power and torque, gasoline engines are equipped, with camshaft adjusters. The camshaft adjusters vary the phase position of the camshaft in relation to the crankshaft driving the camshaft. At the present time, hydraulic vane-cell adjusters with working chambers are mostly used. Adjustment is carried out by means of the controlled admission of oil from the engine lubricating oil circuit into the chambers of the vane cells via a control valve. The control valve is operated by means of a proportional magnet.
DE 198 17 319 C2 discloses a camshaft adjuster of this type which is disposed in the drive of a camshaft driven by the crankshaft. The camshaft adjuster has an inner body which is rotationally fixed with respect to the camshaft. A central tension screw extends through the inner body, which is engaged thereby axially with the camshaft. An outer body is rotatable with respect to the inner body and is driven by the crankshaft. Between the inner body and the outer body, a reception space is provided for hydraulic actuating fluid for rotating the outer body with respect to the inner body. The actuating fluid admission is controlled by a control device with a multiple-way valve in the form of a control slide, the valve being integrated into the tension screw which forms an axial housing for the axially displaceable control slide. The control slide is connected to the armature of an electromagnetic actuating drive which is arranged fixedly with respect to the housing and which comprises an actuating magnet.
For the general technical background, reference is also made to DE 196 11 365 C2, DE 196 54 926 C2 and DE 199 44 535 C1.
It is the object of the present invention to provide a camshaft adjuster which, independently of the lubricating oil pressure of the internal combustion engine, allows high actuating speeds for varying the phase position of the camshaft.